| Current File : //opt/alt/ruby27/share/ruby/csv/table.rb |
# frozen_string_literal: true
require "forwardable"
class CSV
#
# A CSV::Table is a two-dimensional data structure for representing CSV
# documents. Tables allow you to work with the data by row or column,
# manipulate the data, and even convert the results back to CSV, if needed.
#
# All tables returned by CSV will be constructed from this class, if header
# row processing is activated.
#
class Table
#
# Constructs a new CSV::Table from +array_of_rows+, which are expected
# to be CSV::Row objects. All rows are assumed to have the same headers.
#
# The optional +headers+ parameter can be set to Array of headers.
# If headers aren't set, headers are fetched from CSV::Row objects.
# Otherwise, headers() method will return headers being set in
# headers argument.
#
# A CSV::Table object supports the following Array methods through
# delegation:
#
# * empty?()
# * length()
# * size()
#
def initialize(array_of_rows, headers: nil)
@table = array_of_rows
@headers = headers
unless @headers
if @table.empty?
@headers = []
else
@headers = @table.first.headers
end
end
@mode = :col_or_row
end
# The current access mode for indexing and iteration.
attr_reader :mode
# Internal data format used to compare equality.
attr_reader :table
protected :table
### Array Delegation ###
extend Forwardable
def_delegators :@table, :empty?, :length, :size
#
# Returns a duplicate table object, in column mode. This is handy for
# chaining in a single call without changing the table mode, but be aware
# that this method can consume a fair amount of memory for bigger data sets.
#
# This method returns the duplicate table for chaining. Don't chain
# destructive methods (like []=()) this way though, since you are working
# with a duplicate.
#
def by_col
self.class.new(@table.dup).by_col!
end
#
# Switches the mode of this table to column mode. All calls to indexing and
# iteration methods will work with columns until the mode is changed again.
#
# This method returns the table and is safe to chain.
#
def by_col!
@mode = :col
self
end
#
# Returns a duplicate table object, in mixed mode. This is handy for
# chaining in a single call without changing the table mode, but be aware
# that this method can consume a fair amount of memory for bigger data sets.
#
# This method returns the duplicate table for chaining. Don't chain
# destructive methods (like []=()) this way though, since you are working
# with a duplicate.
#
def by_col_or_row
self.class.new(@table.dup).by_col_or_row!
end
#
# Switches the mode of this table to mixed mode. All calls to indexing and
# iteration methods will use the default intelligent indexing system until
# the mode is changed again. In mixed mode an index is assumed to be a row
# reference while anything else is assumed to be column access by headers.
#
# This method returns the table and is safe to chain.
#
def by_col_or_row!
@mode = :col_or_row
self
end
#
# Returns a duplicate table object, in row mode. This is handy for chaining
# in a single call without changing the table mode, but be aware that this
# method can consume a fair amount of memory for bigger data sets.
#
# This method returns the duplicate table for chaining. Don't chain
# destructive methods (like []=()) this way though, since you are working
# with a duplicate.
#
def by_row
self.class.new(@table.dup).by_row!
end
#
# Switches the mode of this table to row mode. All calls to indexing and
# iteration methods will work with rows until the mode is changed again.
#
# This method returns the table and is safe to chain.
#
def by_row!
@mode = :row
self
end
#
# Returns the headers for the first row of this table (assumed to match all
# other rows). The headers Array passed to CSV::Table.new is returned for
# empty tables.
#
def headers
if @table.empty?
@headers.dup
else
@table.first.headers
end
end
#
# In the default mixed mode, this method returns rows for index access and
# columns for header access. You can force the index association by first
# calling by_col!() or by_row!().
#
# Columns are returned as an Array of values. Altering that Array has no
# effect on the table.
#
def [](index_or_header)
if @mode == :row or # by index
(@mode == :col_or_row and (index_or_header.is_a?(Integer) or index_or_header.is_a?(Range)))
@table[index_or_header]
else # by header
@table.map { |row| row[index_or_header] }
end
end
#
# In the default mixed mode, this method assigns rows for index access and
# columns for header access. You can force the index association by first
# calling by_col!() or by_row!().
#
# Rows may be set to an Array of values (which will inherit the table's
# headers()) or a CSV::Row.
#
# Columns may be set to a single value, which is copied to each row of the
# column, or an Array of values. Arrays of values are assigned to rows top
# to bottom in row major order. Excess values are ignored and if the Array
# does not have a value for each row the extra rows will receive a +nil+.
#
# Assigning to an existing column or row clobbers the data. Assigning to
# new columns creates them at the right end of the table.
#
def []=(index_or_header, value)
if @mode == :row or # by index
(@mode == :col_or_row and index_or_header.is_a? Integer)
if value.is_a? Array
@table[index_or_header] = Row.new(headers, value)
else
@table[index_or_header] = value
end
else # set column
unless index_or_header.is_a? Integer
index = @headers.index(index_or_header) || @headers.size
@headers[index] = index_or_header
end
if value.is_a? Array # multiple values
@table.each_with_index do |row, i|
if row.header_row?
row[index_or_header] = index_or_header
else
row[index_or_header] = value[i]
end
end
else # repeated value
@table.each do |row|
if row.header_row?
row[index_or_header] = index_or_header
else
row[index_or_header] = value
end
end
end
end
end
#
# The mixed mode default is to treat a list of indices as row access,
# returning the rows indicated. Anything else is considered columnar
# access. For columnar access, the return set has an Array for each row
# with the values indicated by the headers in each Array. You can force
# column or row mode using by_col!() or by_row!().
#
# You cannot mix column and row access.
#
def values_at(*indices_or_headers)
if @mode == :row or # by indices
( @mode == :col_or_row and indices_or_headers.all? do |index|
index.is_a?(Integer) or
( index.is_a?(Range) and
index.first.is_a?(Integer) and
index.last.is_a?(Integer) )
end )
@table.values_at(*indices_or_headers)
else # by headers
@table.map { |row| row.values_at(*indices_or_headers) }
end
end
#
# Adds a new row to the bottom end of this table. You can provide an Array,
# which will be converted to a CSV::Row (inheriting the table's headers()),
# or a CSV::Row.
#
# This method returns the table for chaining.
#
def <<(row_or_array)
if row_or_array.is_a? Array # append Array
@table << Row.new(headers, row_or_array)
else # append Row
@table << row_or_array
end
self # for chaining
end
#
# A shortcut for appending multiple rows. Equivalent to:
#
# rows.each { |row| self << row }
#
# This method returns the table for chaining.
#
def push(*rows)
rows.each { |row| self << row }
self # for chaining
end
#
# Removes and returns the indicated columns or rows. In the default mixed
# mode indices refer to rows and everything else is assumed to be a column
# headers. Use by_col!() or by_row!() to force the lookup.
#
def delete(*indexes_or_headers)
if indexes_or_headers.empty?
raise ArgumentError, "wrong number of arguments (given 0, expected 1+)"
end
deleted_values = indexes_or_headers.map do |index_or_header|
if @mode == :row or # by index
(@mode == :col_or_row and index_or_header.is_a? Integer)
@table.delete_at(index_or_header)
else # by header
if index_or_header.is_a? Integer
@headers.delete_at(index_or_header)
else
@headers.delete(index_or_header)
end
@table.map { |row| row.delete(index_or_header).last }
end
end
if indexes_or_headers.size == 1
deleted_values[0]
else
deleted_values
end
end
#
# Removes any column or row for which the block returns +true+. In the
# default mixed mode or row mode, iteration is the standard row major
# walking of rows. In column mode, iteration will +yield+ two element
# tuples containing the column name and an Array of values for that column.
#
# This method returns the table for chaining.
#
# If no block is given, an Enumerator is returned.
#
def delete_if(&block)
return enum_for(__method__) { @mode == :row or @mode == :col_or_row ? size : headers.size } unless block_given?
if @mode == :row or @mode == :col_or_row # by index
@table.delete_if(&block)
else # by header
deleted = []
headers.each do |header|
deleted << delete(header) if yield([header, self[header]])
end
end
self # for chaining
end
include Enumerable
#
# In the default mixed mode or row mode, iteration is the standard row major
# walking of rows. In column mode, iteration will +yield+ two element
# tuples containing the column name and an Array of values for that column.
#
# This method returns the table for chaining.
#
# If no block is given, an Enumerator is returned.
#
def each(&block)
return enum_for(__method__) { @mode == :col ? headers.size : size } unless block_given?
if @mode == :col
headers.each { |header| yield([header, self[header]]) }
else
@table.each(&block)
end
self # for chaining
end
# Returns +true+ if all rows of this table ==() +other+'s rows.
def ==(other)
return @table == other.table if other.is_a? CSV::Table
@table == other
end
#
# Returns the table as an Array of Arrays. Headers will be the first row,
# then all of the field rows will follow.
#
def to_a
array = [headers]
@table.each do |row|
array.push(row.fields) unless row.header_row?
end
array
end
#
# Returns the table as a complete CSV String. Headers will be listed first,
# then all of the field rows.
#
# This method assumes you want the Table.headers(), unless you explicitly
# pass <tt>:write_headers => false</tt>.
#
def to_csv(write_headers: true, **options)
array = write_headers ? [headers.to_csv(**options)] : []
@table.each do |row|
array.push(row.fields.to_csv(**options)) unless row.header_row?
end
array.join("")
end
alias_method :to_s, :to_csv
#
# Extracts the nested value specified by the sequence of +index+ or +header+ objects by calling dig at each step,
# returning nil if any intermediate step is nil.
#
def dig(index_or_header, *index_or_headers)
value = self[index_or_header]
if value.nil?
nil
elsif index_or_headers.empty?
value
else
unless value.respond_to?(:dig)
raise TypeError, "#{value.class} does not have \#dig method"
end
value.dig(*index_or_headers)
end
end
# Shows the mode and size of this table in a US-ASCII String.
def inspect
"#<#{self.class} mode:#{@mode} row_count:#{to_a.size}>".encode("US-ASCII")
end
end
end